A gas turbine engine may include a turbine section with multiple rows or stages of stator vanes and rotor blades that interact or react with a high temperature gas flow to create mechanical power (See prior art FIG. 1). In a gas turbine engine, the turbine rotor blades drive the compressor and/or an electric generator to generate electrical power.
The efficiency of the engine can be increased by passing a higher temperature gas flow through the turbine. However, the turbine inlet temperature is limited to the vane and blade (airfoils) material properties and the cooling capabilities of these airfoils. The first stage airfoils are exposed to the highest temperature gas flow since these airfoils are located immediately downstream from the combustor. The temperature of the gas flow passing through the turbine progressively decreases as the rotor blade stages extract energy from the gas flow. The leading edge of the vane and blade airfoils is exposed to high temperature gas flow.
A “high lift” airfoil design is an airfoil shape that allows for reduced airfoil count due to its ability to extract more work than a conventional airfoil. High lift airfoils provide an improvement in efficiency and weight reduction. In using a high lift design, the airfoil stagnation point is shifted from the leading edge nose, where it is located on a conventional airfoil, to the pressure side towards the tip. In addition, the suction side gage line, in which the gas Mach number is at the greatest, on a high lift airfoil occurs much closer to the leading edge nose than a conventional airfoil. Moreover, a High Lift airfoil is defined as an airfoil with a Zweifel load coefficient of greater than 1.1